are moved towards the particles of falt, and joined with them. And when we behold vulgar falt not to flow per deliquium, may we not conclude that the fame law of nature and motion doth not obtain between its particles and thofe of the floating vapours? A drop of water affumes a round figure, because its parts are moved towards each other. But the particles of oil and vinegar have no fuch difpofition to unite. And when flies walk in water without wetting their feet, it is attributed to a repelling force or faculty in the fly's feet. But this is obfcure, though the phænomenon be plain.

236. It is not improbable, and seems not unfupported by experiments, that, as in algebra, where pofitive quantities cease there negative begin, even fo in mechanics, where attracting forces cease there repelling forces begin; or (to exprefs it more properly) where bodies ceafe to be moved towards, they begin to be moved from each other. This Sir Ifaac Newton infers from the production of air and vapours, whofe particles fly afunder with fuch vehement force. We behold iron move towards the loadstone, ftraws towards amber, heavy bodies towards the earth. The laws of these motions are various. And when it is faid, that all the motions and changes in the great world arife from attraction; the elasticity of the air, the motion of water, the descent of heavy, and the afcent of light bodies, being all ascribed to the fame principle; when from infenfible attractions of moft minute particles at the smallest distance are derived cohefion, diffolution, coagulation, animal fecretion, fermentation, and all chemical operations; and when it is said, that without fuch principles there never would have been any motion in the world, and without

the

the continuance thereof all motion would cease. In all this we know or understand no more," than that bodies are moved according to a certain order, and that they do not move themselves.

237. So likewife, how to explain all thofe various motions and effects by the denfity and elafticity of æther, feems incomprehenfible (c). For inftance, why should the acid particles draw thofe of water and repell each other? why fhould fome falts attract vapours in the air, and others not? why fhould the particles of common falt repell each other, fo as not to fubfide in water? why should the most repellent particles be the moft attractive upon contact? Or why fhould the repellent begin where the attractive faculty leaves off. These, and numberless other effects feem inexplicable on mechanical principles, or otherwife than by recourse to a mind or fpiritual agent (b). Nor will it fuffice from prefent phænomena and effects, through a chain of natural caufes and fubordinate blind agents, to trace a divine intellect as the remote original caufe, that firft created the world, and then fet it a going. We cannot make even one fingle ftep in accounting for the phænomena, without admitting the immediate prefence and immediate action of an incorporeal agent, who connects, moves, and difpofes all things, according to fuch rules, and for fuch purposes as feem good to him.

238. It is an old opinion adopted by the moderns, that the elements and other natural bodies are changed each into other (c). Now, as the particles of different bodies are agitated by different forces, attracting and repelling, or, to fpeak more accurately, are moved by different laws, how can these forces

(m) 153, 162. (6) 154, 220.

(c) 148.

or

or laws be changed, and this change accounted for by an elastic æther? Such a medium, diftinct from light or fire, feemeth not to be made out by any proof, nor to be of any ufe in explaining the phænomena. But if there be any medium employed as a fubordinate caufe or inftrument in attraction, it would rather feem to be light (k); fince by an experiment of Mr. Boyle, amber, that fhewed no fign of attraction in the fhade, being placed where the fun-beams fhone upon it, immediately attracted light bodies. Befides, it hath been discovered by Sir Ifaac Newton, and an admirable discovery it was, that light is an heterogeneous medium (1) confifting of particles endued with original diftinct properties. And upon these, if I may venture to give my conjectures, it seemeth probable the specific properties of bodies, and the force of fpecific medicines may depend. Different fides of the same ray fall, one approach and the other recede from the Islandic cryftal; can this be account. ed for by the elafticity of a fine medium, or by the general laws of motion, or by any mechanical principles whatever? And if not, what should hinder but there may be specific medicines, whofe operation depends not upon mechanical principles, how much foever that notion hath been exploded of late years?

239. Why may we not fuppofe certain idiofyncrafies, fympathies, oppofitions, in the folids or fluids or animal fpirit of a human body, with regard to the fine infenfible parts of minerals or vegetables, impregnated by rays of light of different properties, not depending on the different fize, figure, number, folidity, or weight of thofe particles,

(k) 152, 156.

P

(4) 40, 181.

nor

hor on the general laws of motion, nor on the deni fity or elasticity of a medium, but merely and altogether on the good pleasure of the Creator, in the original formation of things? From whence divers unaccountable and unforeseen motions may arife in the animal economy; from whence alfo various peculiar and fpecific virtues may be conceived to arife, refiding in certain medicines, and not to be explained by mechanical principles. For although the general known laws of motion are to be deemed mechanical, yet peculiar motions of the infenfible parts, and peculiar properties depending thereon, are occult and fpecific.

240. The words attraction and repulfion may, in compliance with custom, be used where, accurately fpeaking, motion alone is meant. And in that fenfe it may be faid, that peculiar attractions or repulfions in the parts, are attended with specific properties in the wholes. The particles of light are vehemently moved to or from, retained or rejected by objects. Which is the fame thing as to fay with Sir Ifaac Newton, that the particles of acids are endued with great attractive force (m), wherein their activity confifts; whence fermentation and diffolution; and that the most repellent are, upon contact, the most attracting particles.

241. Gravity and fermentation are received for two most extensive principles. From fermentation are derived the motion and warmth of the heart and blood in animals, fubterraneous heat, fires, and earthquakes, meteors and changes in the atmofphere. And, that attracting and repelling forces operate in the nutrition and diffolution of animal and vegetable bodies, is the doctrine both of Hip

(m) 202,

pocrates

pocrates and Sir Ifaac Newton. The former of these celebrated authors, in his treatise concerning diet or regimen, obferves, that in the nourishment of man, one part repells and another attracts. And again, in the fame treatise, two carpenters, faith he, faw a piece of timber; one draws, the other pushes; these two actions tend to one and the fame end, though in a contrary direction, one up, the other down: This imitates the nature of man: πνεῦμα τὸ μὲν ἕλκει, τὸ δὲ ὠθέει.

242. It is the general maxim of Hippocrates, that the manner wherein nature acts confifteth in attracting what is meet and good, and in repelling what is difagreeable or hurtful. He makes the whole of the animal oeconomy to be administered by the faculties or powers of nature. Nature alone, faith he, fufficeth for all things to animals. She knows of herself what is neceffary for them. Whence it is plain, he means a confcious intelligent nature, that prefides and moves the ætheriał fpirit. And tho' he declares all things are accomplifhed on man by neceffity, yet it is not a blind fate or chain of mere corporeal caufes, but a divine neceffity, as he himself exprefly calls it. And what is this but an over-ruling intelligent power that difpofeth of all things?

243. Attraction cannot produce, and in that fenfe account for the phænomena, being itself one of the phænomena produced and to be accounted for (n). Attraction is performed by different laws, and cannot therefore in all cafes be the effect of the elasticity of one uniform medium. The phænomena of electrical bodies, the laws and variations of magnetism, and, not to mention other kinds, even

(n) 160, 235.

P 2

gras